On the package of the US-05 it says it's temperature range is 58-75F. However, all the reading on forums I am finding people tend to the lower end of the spectrum, even calling upper-60's to be too high.

This is my first time brewing and I'm in SE Asia using a DIY cooler. Room temps here are between 82F and 88F. I'm able to get the ambient temp in the cooler down to 64-66F and the temp on the fermenter has been a consistent 70F. Are these temps ok for an IPA? Should I try and get my ambient down closer to 60F? I do enjoy that 'grapefruit' flavour and best I can tell that happens at the higher-end of the temp scale, but I just want to be sure.

3 Answers
3

70F is high for US-05, and not ideal at all. However, if you beer has been fermenting for a few days, its (a) too late to do anything, and (b) risky to drop the temp anyway, since you might shock the yeast into going dormant too early.

Regarding (a), the flavors created by the yeast mostly occur within the first 3 days of fermentation, that is when temp control is the most important. Roughly speaking, more yeast = less yeast flavor, and cooler temps = less yeast flavor. These are ROUGH ballparks (some strains do very different things at different temps) but true enough to be a general rule of thumb.

Regarding (b), you don't want to drop the temp of fermenting yeast ever, in my opinion. Some strains are very cold-sensitive this way, and if you drop the temp more than a few degrees within a short time, they will "go to sleep" and start to drop out of suspension. If the beer is totally done, then great! But if not, then you have problems (sweet beer, funky flavors, bottle bombs(!), etc).

The yeast doesn't produce "grapefruit" though, that's 100% from the hops you use. Centennial is the most "grapefruity" to me, and Cascade is close too. Any of the "American-C" hops will get you there, especially if you use them in the last 10min of the boil or dry hop with them.

Thanks! I am using Cascade hops, so maybe that's what the homebrew guy was talking about with regard to the grapefruit flavour. Interesting how the yeast package said the range goes up to 75F when 70F would be considered too high, doesn't seem like a negligible amount on the part of the manufacturer. I will keep that in mind for the future. I'll keep the current course I'm on with temp, it just read 69F on the outside of the fermenter. What would be considered a short time to drop a couple of degrees?
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ntmwOct 22 '12 at 15:08

I wouldn't drop more than 5-7 degrees in 24 hours without being concerned about the yeast stalling, depending on the strain.
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GrahamOct 22 '12 at 18:05

I routinely ferment US-05 at 68F and it is still very clean despite others reporting in at 60F.
At 70F you'll be fine. US-05 is a great yeast and very versatile across that whole range.

In fact, unless you've already really mastered the yeast starter and the proper amount of O2 in your beer, attempting to ferment at 60F will be difficult and likely lead to a slow ferment or a stuck ferment. Which would be worse than fermenting at 70F IMO.

Good to know. I was told this yeast would be good for an American IPA, I didn't know it was so versatile. I'll stay the course at 70F and look forward to seeing how it turns out.
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ntmwOct 23 '12 at 1:50